Precision stamping press



Jim. W, 1967 w. WANNER 3,296,912

PRECISION STAMPING PRESS Filed April 8, 1965 3 Sheets-Sheet 1 Jan, 19, 1967 w, WANNER 3,296,912

PRECISION STAMPING PRESS Filed April 8, 1965 5 SheetsSheet 2 Oberes Uni'eres. Ausslossen Ausblo bggfm Hubendefz Hubende Vorschub az s s I 2 1 l l I Q I i gasa sa a Jan. 10, 1967 w. WANNER 3,

PRECISION STAMPING PRESS Filed April 8, 1965 3 Sheets-Sheet 5 INVENTOR WALTER WAN/VER 3,296,912 PRECESKON STAMPING PRESS Waiter Wanner, Romanshorn, Thurgau, Switzerland, assignor to Hydrel A.G., litomanshorn, Thurgan, Switzerland Filed Apr. 8, 1965, Ser. No. 446,626 Claims priority, application Switzerland, Apr. 10, 1964, 4,593/64 12 Claims. (4C1. 83-461) The invention relates to a precision stamping press with a cutter piston, a main piston for pressing the workpiece on to the bed plate, and a counterpressure piston for supporting the part of the workpiece which is to be stamped. The object of the invention is to make a machine for carrying out precision stamping which allows production of stampings with clean, right-angled cut surfaces with little surface roughness, and which also allows a large number of strokes, i.e. great economy of productlon.

According to the invention the cutter piston is arranged coaxially with and inside the main piston and is movable relative to this piston, both pistons are arranged in a common cylinder and the cutter piston is linked by a piston rod to a yoke which is connected in turn to pistons of compressed-air cylinders, and the working stroke of the combined cutter and main piston is regulated hydraulically, whereas the return stroke is regulated by means of compressed air.

The invention will now be described, by way of example only, with reference to the accompanying drawings. In these:

FIG. 1 is a schematic side View of a precision stamping press, partly in section;

FIG. 2 is a front view of the upper part of a control panel;

FIG. 3 is a rear view of the control panel shown in FIG. 2, and

FIG. 4 is a view similar to FIG. 1 but showing a wiring diagram for the electronic time delay device.

As FIG. 1 shows, the press comprises a base A in the form of an oil tank containing hydraulic pumps 1, hydraulic regulating members 2 and oil filtering means 3. On the base A there is a bed plate 4 with a counterpressure piston and cylinder 5a built into it. Above this, on four connecting pillars 6, there is the upper part B of the press, consisting primarily of a cutter piston 7, a main piston 8 and a cylinder 9 whose top is a flange plate 10 receiving two compressed-air cylinders 11, 12 with pistons 11a, 12a arranged in parallel and having prestressed springs 13, 14 for operating a movable yoke 15. The yoke 15 is linked to the cutter piston 7 by a piston rod 7a. In a fixed yoke 16 there is a set screw 17 for adjusting a stop flange 13 which limits the upward movement of the movable yoke 15. The stop for the downward movement of the movable yoke 15 is set by turning intermeshing threaded cylinders 19, 20. These are finely adjusted by means of a handwheel 21 by way of a worm 22 on a cog attached directly to the bottom of the outside threaded cylinder 2%, while high-speed adjustment of the lower stamping stroke stop i carried out with a geared motor 23 by way of two bevel gears 24.

For the working stroke the pistons 7, 8 are moved by feeding pressure oil into the cylinder chamber 9a through the line 35. The return stroke of the combined cutter and main piston 7, 8 is effected by way of the movable yoke 15 by means of the two parallel air pistons 11a, 12a in the compressed air cylinders 11, 12, which by means of the two additional compression springs 13, 14 prevent the combined cutter and main piston 8, 9 from falling if there is no, or is not enough, air pressure. Pro-stressed 3,295,912 Patented Jan. 10, 1967 compression springs 25 are arranged on the bottom face of the cutter piston 7 and supported on the bottom flange of the main piston it so that after completion of the cutting movement the cutter piston 7, with the stamping tool (not shown) attached to it, can be retraced at high speed by the equivalent of its play in the main piston 8. The stamping tool is thus withdrawn from the band of material to be stamped (not shown) very quickly, allowing the latter to be fed onwards without delay.

A band guide (not shown) on the side of the bottom of the upper part of the tool block serves to raise the material of the band from the cutting die, so that after every cutting movement and after the ejection of the stamping from the cutting die by the counterpressure piston 5 there is a clear view of the bed plate 4 and especially of the lower part of the tool block, allowing easy supervision by eye or with optical/electrical apparatus of the ejection effected and the blowing-off or mechanical removal of the stamping and the stamping scrap. Where desired, e.g. in the case of automatic precision stamping from a roll, the feed mechanism for the band material can be operated with the same regulating pulse that is required for blowing off or mechanically removing the stampings and scrap.

Precision stamping requires very accurate reversing of the cutter piston 7 at the lower reversing point. This can be done either with the threaded stop cylinder 19, adjustable by hand or by an electric motor, or by means of an adjustable electrical control system at the operators eye level. A suitable electrical control system is shown in FIGS. 2 and 3. The upper and lower reversing points of the combined cutter and main piston 7, 8, the upper reversing point of the counterpressure piston 5, and the time for starting the air blast or a mechanical feed for removing the stamping and the stamping scrap, can be varied by means of adjustable graduated knobs as, 27, 2.3, 29, while at the same time microswitches 36 (FIG. 3) connected behind the front panel to the control knobs 2629 are moved so that they send a reversing pulse to the hydraulic control mechanism of the relevant piston system when the pistons concerned reach the desired height. This is done by providing the upper and lower piston units with tripping pins 31 variable in height, which operate the microswitches 39 when the pistons move.

To ensure that the cutter piston 7 will press the cutting stamp into the cutting die at the lower reversing point, and to make the electrical reversing of the hydraulic by way of the microswitch 27 on the control panel (FIGS. 2, 3) reliable, which is otherwise impossible, the switch 27 i connected in dependence on an electronic timing relay so that the mechanical control pulse for this switch is sent out before the press yoke 15 strikes the threaded cylinder 1d.

The hydraulic regulating mechanism for the counterpressure piston 5 is designed so that the piston is momentarily stationary at the lower reversing point, i.e. reversing is delayed. The stamping is thus only ejected by the rise of this piston from the cutting die in the lower part of the tool block when the band of material has also been raised from the cutting die by the combined cutter and main piston when the latter is lifted.

In FIG. 4, there is shown the electronic time delay control device 36, in a simple relay circuit including a pin actuated switch 31' adapted to be closed by actuation of the pin 31 which energizes the relay 41. Relay 41 is then energized to close the switches 41/ and 41/ A circuit is thus established through the relay 42 and when the relay 42 is energized the switch 4-2/ is closed. The pin 31 in its downward movement actuates the switch contact elements 51 and 52 of the micro-switches 30 so that the pin 31 will permit the switch 52 to close prior to the engagement of the plate with the member 19 and thus establish a circuit through the potentiometer 61 which delays the energization of the solenoid 44 and the opening of the circuit through the solenoid 42 before the plate 15 strikes the threaded cylinder 19.

The end switch 53 gives a discharge impulse and the end switch 54 gives a blowout impulse, while the end switch 51 opens the holding circuit for the relay 44. The compressing cycle starts again if the switch 31 is still closed. All auxiliary functions are added to the circuit. The switch elements 51 and 52 represent the end switch for the upper stroke and the end switch for the lower stroke, while the switches 53 and 54 are intended for the pressure piston actuated discharge, and for blowout respectively.

What is claimed is:

1. A precision stamping press comprising: a bed plate; means for supporting part of a workpiece on said bed plate; said means comprising a counterpressure piston; means holding a cylinder spaced from said bed plate; an end wall in the cylinder; a main piston in the cylinder; a cylinder chamber defined between said end wall and said main piston; a cutter piston coaxially arranged within said main piston; a first end and a second end on said cutter piston; a stamping face at said first end; a piston rod extending from said cutter piston at said second end and through said end wall; a yoke on said piston rod; pneumatic displacement means disposed between said yoke and said cylinder; 21 fluid pressure conduit leading into said chamber and a hydraulic pressure source communicating with said fluid pressure conduit.

2. A precision stamping press comprising: a bed plate; means for supporting part of a workpiece on said bed plate; said means comprising a counterpressure piston; means holding a cylinder spaced from said bed plate; an end wall in the cylinder; a main piston in the cylinder; a cylinder chamber defined between said end wall and said main piston; a cutter piston coaxially arranged inside said main piston; said cutter piston being slidable axially within said main piston; a first end and a second end on said cutter piston; a stamping face at said first end; a piston rod extending from said cutter piston at said second end and through said end wall; a yoke on said piston rod; pneumatic displacement means disposed between said yoke and said cylinder; a fluid pressure conduit leading into said chamber and a hydraulic pressure source communicating with said fluid pressure conduit.

3. A press according to claim 2, in which compression springs are disposed between said main piston and said cutter piston.

4. A precision stamping press comprising: a bed plate; means for supporting part of a workpiece on said bed plate; said means comprising a counterpressure piston; means holding a cylinder spaced from said bed plate; an end wall in the cylinder; 21 main piston in the cylinder; a cylinder chamber defined between said end wall and said main piston; a cutter piston coaxially arranged inside said main piston; said cutter piston being slidable axially within said main piston; compression springs between said main piston and said cutter piston; a first end and a second end on said cutter piston; a stamping face at said first end; a piston rod extending from said cutter piston at said second end and through said end wall; a yoke on said piston rod; pneumatic displacement means disposed between said yoke and said cylinder; spring means urging said yoke away from said cylinder; a fluid pressure conduit leading into said chamber and a hydraulic pressure source communicating with said fluid pressure conduit.

5. A press as claimed in claim 4 including mechanical stop means controlling the length of stroke of said cutting piston and said main piston.

6. A precision stamping press comprising: a bed plate; means for supporting part of a workpiece on said bed plate; said means comprising a counterpressure piston; means holding a cylinder spaced from said bed plate; an end wall in the cylinder; a main piston in the cylinder; a

cylinder chamber defined between said end wall and said main piston; a cutter piston coaxially arranged inside said main piston; said cutter piston being slidable axially within said main piston; compression springs between said main piston and said cutter piston; a first end and a second end on said cutter piston; 21 stamping face at said first end; a piston rod extending from said cutter piston at said second end and through said end wall; a yoke on said piston rod; pneumatic displacement means disposed between said yoke and said cylinder; spring means urging said yoke away from said cylinder; a fluid pressure conduit leading into said chamber; a hydraulic pressure source communicating with said fluid pressure conduit; mechanical stop means controlling the length of stroke of said cutting piston and said main piston; said mechanical stop means incorporating tripping pins operatively connectable with regulating members; and said regulating members being adapted to open and close said hydraulic fluid supply source.

7. A press according to claim 6 in which said tripping pins engage with micro-switches.

8. A precision stamping press comprising: a bed plate; means for supporting part of a workpiece on said bed plate; said means comprising a counterpressure piston; means holding a cylinder spaced from said bed plate; an end wall in the cylinder; a main piston in the cylinder; a cylinder chamber defined between said end wall and said main piston; a cutter piston coaxially arranged inside said main piston; said cutter piston being slidable axially within said main piston; compression springs between said main piston and said cutter piston; a first end and a second end on said cutter piston; a stamping face at said first end; a piston rod extending from said cutter piston at said second end and through said end wall; a yoke on said piston rod; pneumatic displacement means disposed between said yoke and said cylinder; spring means urging said yoke away from said cylinder; at fluid pressure conduit leading into said chamber; and a hydraulic pressure source communicating with said fluid pressure conduit; mechanical stop means controlling the length of stroke of said cutting piston and said main piston; said mechanical stop means incorporating tripping pins operatively connectable with regulating members; said regulating members being adapted to open and close said hydraulic fluid supply source; said cutter piston having an upper reversing point and a lower reversing point; reversing means for reversing said cutter piston at said lower reversing point; electronic timing relay means associated with said reversing means; said electronic timing relay being adjustable as regards duration of effect.

9. A precision stamping press comprising: a bed plate; means for supporting part of a workpiece on said bed plate; said means comprising a counterpressure piston; means holding a cylinder spaced from said bed plate; an end wall in the cylinder; a main piston in the cylinder; a cylinder chamber defined between said end wall and said main piston; a cutter piston coaxially arranged inside said main piston; said cutter piston being slidable axially within said main piston; compression springs between said main piston and said cutter piston; a first end and a sec ond end on said cutter piston; a stamping face at said first end; a piston rod extending from said cutter piston at said second end and through said end wall; a yoke on said piston rod; pneumatic displacement means disposed between said yoke and said cylinder; spring means urging said yoke away from said cylinder; a fluid pressure conduit leading into said chamber; a hydraulic pressure source communicating with said fluid pressure conduit; mechanical stop means controlling the length of stroke of said cutting piston and said main piston; said mechanical stop means being triggered by said cutter piston and said main piston; said mechanical stop means incorporating tripping pins operatively connectable with regulating members; said regulating members being adapted to open and close said hydraulic fluid supply source; an intermeshing threaded Cy der. on said piston rod; stop means for engaging with said intermeshing threaded cylinder; means for controlling the position of said intermeshing threaded cylinder on said piston; the position of said intermeshing threaded cylinder regulating the lower mechanical stopping point for said main piston and said cutter piston.

10. A press according to claim 9 in which the position of said intermeshing threaded cylinder is adjustable by hand operated means.

11. A press according to claim 9 in which the position of the intermeshing threaded cylinder is adjustable by electric motor means.

12. A precision stamping press comprising a bed plate; means for supporting part of a workpiece on said bed plate; said means comprising a counterpressure piston; means for ejecting a stamping formed on said workpiece; means holding a cylinder spaced from said bed plate; an end wall in the cylinder; a main piston in the cylinder; a cylinder chamber defined between said end wall and said main piston; a cutter piston coaxially arranged inside said rnain piston; said cutter piston being slidable axially within said main piston; a first end and a second end on said cutter piston; a stamping face at said first end; a piston rod extending from said cutter piston at said second end and through said end wall; a yoke on said piston rod; pneumatic displacement means disposed between said yoke and said cylinder; spring means urging said yoke away from said cylinder; a fluid pressure conduit leading into said chamber; a hydraulic pressure source communicating with said fluid pressure conduit; mechanical stop means controlling the length of stroke of said cutting piston and said main piston; said mechanical stop means being triggered by said cutter piston and said main piston; said stop means incorporating tripping pins operatively connectable with regulating members; said regulating members being adapted to open and close said hydraulic fluid supply source.

References Cited by the Examiner UNITED STATES PATENTS ANDREW R. JUHASZ, Primary Examiner. 

1. A PRECISION STAMPING PRESS COMPRISING: A BED PLATE; MEANS FOR SUPPORTING PART OF A WORKPIECE ON SAID BED PLATE; SAID MEANS COMPRISING A COUNTERPRESSURE PISTON; MEANS HOLDING A CYLINDER SPACED FROM SAID BED PLATE; AN END WALL IN THE CYLINDER; A MAIN PISTON IN THE CYLINDER; A CYLINDER CHAMBER DEFINED BETWEEN SAID END WALL AND SAID MAIN PISTON; A CUTTER PISTON COAXIALLY ARRANGED WITHIN SAID MAIN PISTON; A FIRST END AND A SECOND END ON SAID CUTTER PISTON; A STAMPING FACE AT SAID FIRST END; A PISTON ROD EXTENDING FROM SAID CUTTER PISTON AT SAID SECOND END AND THROUGH SAID END WALL; A YOKE ON SAID PISTON ROD; PNEUMATIC DISPLACEMENT MEANS DISPOSED BETWEEN SAID YOKE AND SAID CYLINDER; A FLUID PRESSURE CONDUIT LEADING INTO SAID CHAMBER AND A HYDRAULIC PRESSURE SOURCE COMMUNICATING WITH SAID FLUID PRESSURE CONDUIT. 